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  • 1
    Online Resource
    Online Resource
    Prolonged treadmill running in normobaric hypoxia causes gastrointestinal barrier permeability and elevates circulating levels of pro- and anti-inflammatory cytokines
    Canadian Science Publishing ; 2020
    In:  Applied Physiology, Nutrition, and Metabolism Vol. 45, No. 4 ( 2020-04), p. 376-386
    Details
    In: Applied Physiology, Nutrition, and Metabolism, Canadian Science Publishing, Vol. 45, No. 4 ( 2020-04), p. 376-386
    Abstract: This study examined the impact of treadmill running in normobaric hypoxia on gastrointestinal barrier permeability and the systemic inflammatory response. Ten recreationally active participants completed two 1-h bouts of matched-workload treadmill exercise (65% normoxic maximal oxygen consumption) in counterbalanced order. One bout was performed in normoxia (NORM: fraction of inspired oxygen (F I O 2 ) = 20.9%) and the other in normobaric hypoxia (HYP: F I O 2 = 13.5%). Minute ventilation, respiratory rate (R R ), tidal volume (V T ), oxygen consumption, carbon dioxide production, respiratory exchange ratio (RER), and heart rate (HR) were measured with a metabolic cart. Peripheral oxygen saturation (SpO 2 ) was measured with pulse oximetry. Absolute tissue saturation (StO 2 ) was measured with near-infrared spectroscopy. Fatty acid-binding protein (I-FABP) and circulating cytokine concentrations (interleukin (IL)-1Ra, IL-6, IL-10) were assayed from plasma samples that were collected pre-exercise, postexercise, 1 h-postexercise, and 4 h-postexercise. Data were analyzed with 2-way (condition × time) repeated-measures ANOVAs. Newman–Keuls post hoc tests were run where appropriate (p 〈 0.05). As compared with NORM, 1 h of treadmill exercise in HYP caused greater (p 〈 0.05) changes in minute ventilation (+30%), R R (+16%), V T (+10%), carbon dioxide production (+18%), RER (+16%), HR (+4%), SpO 2 (–16%), and StO 2 (–10%). Gut barrier permeability and circulating cytokine concentrations were also greater (p 〈 0.05) following HYP exercise, where I-FABP was shown increased at postexercise (+68%) and IL-1Ra at 1 h-postexercise (+266%). I-FABP and IL-1Ra did not change (p 〉 0.05) following NORM exercise. IL-6 and IL-10 increased with exercise in both study conditions but were increased more (p 〈 0.05) following HYP at postexercise (+705% and +127%, respectively) and 1 h-postexercise (+400% and +128%, respectively). Novelty Normobaric hypoxia caused significant desaturation and increased most cardiopulmonary responses by 10%–30%. Significant gut barrier permeability and increased pro- and anti-inflammatory cytokine concentrations could promote an “open window” in the hours following HYP exercise.
    Type of Medium: Online Resource
    ISSN: 1715-5312 , 1715-5320
    URL: Article
    DOI: 10.1139/apnm-2019-0378
    Language: English
    Publisher: Canadian Science Publishing
    Publication Date: 2020
    SSG: 31
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  • 2
    Online Resource
    Online Resource
    Reduced inflammatory and phagocytotic responses following normobaric hypoxia exercise despite evidence supporting greater immune challenge
    Canadian Science Publishing ; 2020
    In:  Applied Physiology, Nutrition, and Metabolism Vol. 45, No. 6 ( 2020-06), p. 628-640
    Details
    In: Applied Physiology, Nutrition, and Metabolism, Canadian Science Publishing, Vol. 45, No. 6 ( 2020-06), p. 628-640
    Abstract: This study examined changes in immune markers following sustained treadmill exercise in normobaric hypoxia. Ten subjects performed 1 h of treadmill exercise (65% maximal oxygen uptake) under normoxic (NORM: fraction of inspired oxygen (F I O 2 ) = 20.9%) and normobaric hypoxic (HYP: F I O 2 = 13.5%) conditions. Blood samples, collected before, after (Post), 1 h after (1-Post), and 4 h after (4-Post) exercise, were assayed for plasma cytokines (interleukin (IL)-1RA/IL-1β/IL-8/tumor necrosis factor alpha (TNF-α)) and markers of leukocyte activation (macrophage inflammatory protein-1β (MIP-1β)/myeloperoxidase (MPO)/soluble intercellular adhesion molecule-1 (sICAM-1)) using ELISA. Pro- to anti-inflammatory cytokine ratios (TNF-α/IL-1RA; IL-1β/IL-1RA) were calculated. Peripheral blood mononuclear cells (PBMC) were analyzed for changes in inflammatory status (phosphorylated nuclear factor kappa B/nuclear factor kappa B) using Western Blot. Data were analyzed with 2-way (condition × time) repeated-measure ANOVAs with Newman–Keuls post hoc tests. MIP-1β was elevated at 1-Post HYP exercise (+11%; p 〈 0.01) but did not increase following exercise in NORM. TNF-α/IL-1RA and IL-1β/IL-1RA ratios were both reduced (p 〈 0.05) following HYP exercise (−16% and −52%, respectively, at 1-Post and −7% and −32%, respectively, at 4-Post). IL-8 increased (p 〈 0.05) at Post and 1-Post NORM (+33% and +57%, respectively) and HYP (+60% and +83%, respectively) exercise, but was not different between conditions (p 〉 0.05). Interestingly, plasma sICAM-1 did not increase (p 〉 0.05) following NORM exercise but was increased (p 〈 0.05) at Post (+17%), 1-Post (+16%), and 4-Post (+14%) HYP exercise. There was also a delayed peak in plasma MPO concentrations following HYP exercise and PBMC exhibited a reduced (p 〈 0.05) inflammatory capacity at Post (−38%) and 1-Post (−49%). Novelty Following HYP exercise, participants exhibited (i) circulatory bias towards anti-inflammation; (ii) elevated sICAM; (iii) delayed peak in plasma MPO; and (iv) diminished inflammatory response in PBMC. Collectively, these data suggest immunosuppression. This is undesirable, given that elevated MIP-1β (reported here) and elevated intestinal fatty acid binding protein (reported previously) both suggest higher lipopolysaccharide concentrations following HYP exercise.
    Type of Medium: Online Resource
    ISSN: 1715-5312 , 1715-5320
    URL: Article
    DOI: 10.1139/apnm-2019-0657
    Language: English
    Publisher: Canadian Science Publishing
    Publication Date: 2020
    SSG: 31
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  • 3
    Online Resource
    Online Resource
    The Northwest Territories Thermokarst Mapping Collective: A northern-driven mapping collaborative toward understanding the effects of permafrost thaw
    Canadian Science Publishing ; 2023
    In:  Arctic Science
    Details
    In: Arctic Science, Canadian Science Publishing
    Abstract: This paper documents the first comprehensive inventory of thermokarst and thaw-sensitive terrain indicators for a 2 million km2 region of northwestern Canada. This is accomplished through the Thermokarst Mapping Collective (TMC), a research collaborative to systematically inventory indicators of permafrost thaw sensitivity by mapping and aerial assessments across the Northwest Territories (NT), Canada. The increase in NT-based permafrost capacity has fostered science leadership and collaboration with government, academic, and community researchers to enable project implementation. Ongoing communications and outreach have informed study design and strengthened Indigenous and stakeholder relationships. Documentation of theme-based methods supported mapper training, and flexible data infrastructure facilitated progress by Canada-wide researchers throughout the COVID-19 pandemic. The TMC inventory of thermokarst and thaw-sensitive landforms agree well with fine-scale empirical mapping (69% to 84% accuracy) and aerial inventory (74% to 96% accuracy) datasets. National- and circumpolar-scale modelling of sensitive permafrost terrain contrasts significantly with TMC outputs, highlighting their limitations and the value of empirically-based mapping approaches. We demonstrate that the multi-parameter TMC outputs support a holistic understanding and refined depictions of permafrost terrain sensitivity, provide novel opportunities for syntheses, and inform future modelling approaches, which are urgently required to comprehend better what permafrost thaw means for Canada’s North.
    Type of Medium: Online Resource
    ISSN: 2368-7460
    URL: Article
    DOI: 10.1139/AS-2023-0009
    Language: English
    Publisher: Canadian Science Publishing
    Publication Date: 2023
    detail.hit.zdb_id: 3037411-X
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